PC not connecting to wireless router

[Maladict]

My PC stopped connecting to the router all of a sudden. My laptop and mobile phones are still connecting fine.
Accessing the router I see it is aware of the PC but lists its IP as 0.0.0.0.
The only thing I can think of is a faulty wifi-adapter, anyone got a better idea before I get a new one?

[Vricklund]

1. Make sure the computer is not set to a static IP. If you've been playing around with file and printer sharing it's possible windows mucked up your settings.
2. Check that your network device has a TCP-protocol (IPv4) otherwise install it.

[Maladict]

No, that's not it, thanks. I haven't changed anything for months, except changing the wifi channel on the router because of interference from the neighbours.
Reset the router to factory settings, still no difference. Only the desktop pc won't connect.

[Grey Fox]

Try disabling all wired connection devices and the wifi, then enable wifi back.

Maybe new wifi channel has too many interference near where your PC to connect effectively.

[Vricklund]

3. Try deleting all the saved wireless networks and reboot.
4. Reinstall the adapter drivers.

For diagnostics it would be interesting to know if it works with encryption disabled. Also if it works with static IP settings. If you run ipconfig /all from the prompt does anything look strange?

[Maladict]

Try disabling all wired connection devices and the wifi, then enable wifi back.

Maybe new wifi channel has too many interference near where your PC to connect effectively.

No, I've tried a few different channels. There are no wired connections.

[Liep]

Pull the plug on the router and wait 15 seconds. Also, if you use mac filtering I've once experienced my router just discarded my phone's address, that was a frustrating troubleshoot.

[Maladict]

3. Try deleting all the saved wireless networks and reboot.
4. Reinstall the adapter drivers.

For diagnostics it would be interesting to know if it works with encryption disabled. Also if it works with static IP settings. If you run ipconfig /all from the prompt does anything look strange?

Default gateway is blank, otherwise nothing looks strange.

[Maladict]

Pull the plug on the router and wait 15 seconds.

First thing I tried 

[Maladict]

Trying static IP seems to work only on the third attempt 
The only downside is that I seem to have locked myself out of the router, must have inadvertently changed the password.
Thanks all for the help. 

[Vricklund]

Then there's probably nothing physically wrong with your network adapter. Somehow your desktop isn't getting it's IP via DHCP and chances are it's a user issue. When you ipconfig'ed was IP 0.0.0.0 there as well or something else? If windows can't find a DHCP server then it defaults to an IP in the 169.254.x.x range.

Ctrl+Alt+Del and click on services, is the DHCP client running? Do you have a software firewall/antivirus program running on your desktop? The DHCP client listens on tcp/udp port 68.

[Maladict]

IP was in the 169.x.x.x range. DHCP is running, well actually it's stopped.
The windows firewall is off, I get an error message trying to turn it on. Other than that I only have MS Security Essentials running.

[Grey Fox]

You got XP, right?

The firewall error is probably what's causing your problem.

[Maladict]

You got XP, right?

The firewall error is probably what's causing your problem.

Win7

[Vricklund]

Sounds weird indeed. Why is DHCP stopped, because you're using static or is something perventing it from starting (I'm thinking firewall too)? Look at the microsoft databases there seems to be a number of similar problems with DHCP and firewalls.